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Pinpointing cause of out of focus subject

 
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AlexC



Joined: 18 Apr 2019
Posts: 12
Location: Oregon

PostPosted: Wed Apr 24, 2019 12:04 am    Post subject: Pinpointing cause of out of focus subject Reply with quote

Just beginning to get my rig together, and started to take some test shots. Unfortunately they all seem to be out of focus, and this seems to be the entire image and not just outside of the focal area. I'm wondering if someone more experienced can tell me what might be the cause of this.

I would like the set up is sturdy and mostly free of vibration, its mounted on a steel plate and doesn't seem to have vibration that is out of control, although I'm sure it would have some problems at high magnifications.

Equipment:

Nikon d3500
PB-5 Bellows on Manual focusing Rail
LED flash
Nikon AF-P Nikkor 18-55mm VR 1:3.5-5.6 G



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Chris S.
Site Admin


Joined: 05 Apr 2009
Posts: 3279
Location: Ohio, USA

PostPosted: Wed Apr 24, 2019 12:49 am    Post subject: Reply with quote

Alex,

I doubt that the softness in these images is caused by their being out of focus. More likely, the cause is one or both of two other issues.

One, an LED flash typically illuminates the subject for far too long to eliminate vibration as a source of softness. And for people newly entering high-magnification photography, vibration is all-too-often a huge issue. To test this, you will need to get some speedlights, or studio flashes with available settings with very short flash duration (many, but not all, studio flashes have long flash durations--check before you buy.)

Two, your lens may be the limiting factor. A Nikon AF-P Nikkor 18-55mm VR 1:3.5-5.6 G is a “kit lens”—designed to be sold with a camera body at a low price point. In the Nikon world, kit lenses tend to be surprisingly good when used in normal shooting. But here, you are pushing this lens well beyond its designed intent.

Do you know what magnification you’re shooting at? (To find out, try shooting a finely-marked ruler at the same bellows extension; then compare how much of the ruler you record with the size of your sensor. Feel free to list your findings and ask for guidance on how to interpret them.) If your magnification is higher than 1x (aka 1:1), you should at least be reversing your lens (shooting backwards through it). Better, you should be choosing a lens known to perform well at this magnification. If you share your magnification with us, we can point you to lenses known to be good at this mag.

A sobering reality of photographing small things: It takes a lot of lenses to obtain high quality coverage over a surprisingly small range of fields of view. For general photography, even a picky photographer may get by with a 14-24mm zoom, a 24-70mm zoom, and an 80-400mm zoom—or some similar set. But for macro/micro work, a similarly picky photographer might need specific lenses for 1x, 2-3x, 5x, 10x, 20x, 50x, and 100x. And an even more picky photographer might supplement this list with additional lenses. Many of us here fall into this “even more picky” category, and have a lot of lenses for taking pictures of small things.

I'm not condemning you to buying lots of lenses*; rather, if you tell us more about what magnification range you want to shoot, we can recommend optics for that range.

Cheers,

--Chris S.

*Unless you fall down the rabbit hole that many of us are in, where we Must Have Capability to photograph pretty much anything small with world-class results. If so, you're doomed to spend as we do--but at least we can help guide you! Very Happy
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AlexC



Joined: 18 Apr 2019
Posts: 12
Location: Oregon

PostPosted: Wed Apr 24, 2019 3:58 am    Post subject: Reply with quote

Thank you for the response Chris! Still learning my way around cameras, and the terminology, but you're correct. My assumption was that it was in focus, but because of other factors the image doesn't have the contrast it should.

I do have a few microscope objectives I plan on using, just waiting for the RMS adapter. In the mean time I planned on using the nikkor lens. I assumed incorrectly that this would work just fine, so thank you.

I'll get a ruler with fine increments, and post the results along with a corresponding image. Again, thanks for the help. As for the rabbit hole, I think I'm beginning to fall down it, lots to learn, but its a lot of fun. I've definitely spent a lot of time this past week or so ingesting as much info as I can.
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Yawns



Joined: 20 Dec 2015
Posts: 333
Location: Benavente, Portugal

PostPosted: Wed Apr 24, 2019 4:08 pm    Post subject: Reply with quote

1. Are you using "live mode" (Mirror up) while shoting? That helps a bit ...

Another thing that helps with Nikon is to shoot with "Exposure delay ON"... fierst the camera lifts the mirror and only opens the curtains a little latr.. that hepls to reduce the curtains kick effect...
The bad news is the Nikon D3XXX don't have that option in the menus.

2. I never used the 18-55 in the rail.. but I got it a few times out to the grass for curiosity and for the fun.... with tubes and straight.


alt low magnifications it's pretty "ok" and may return pleaseant pictures...

empusa pennata 0006 by antonio caseiro, on Flickr

but when pushed a little closer the limitations start to show up...

empusa pennata 0007 by antonio caseiro, on Flickr
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AlexC



Joined: 18 Apr 2019
Posts: 12
Location: Oregon

PostPosted: Tue May 21, 2019 4:02 pm    Post subject: Reply with quote

Sorry for the late reply, but I realized I was missing some key components to start getting good images. I've now since bought a wemacro rail, and RMS adapter for the bellows.

The sharpness of the image has improved greatly but I do still see some flaws, and am hoping some of you more experienced could help out. This stack was 252 images (Helicon). Right off the bat I realize that lighting and exposure are really bad, and around the hairs there seems to be problems with the algorithm used in Helicon. Any advice?

I believe the each image was a step of 11um, but I can't remember exact settings. exposure was 1/3s with a rear synced dual LED flash. The flash was diffused with pieces of foam about 1/8th inch thick.

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